Input: tsc2005 - fix locking issue

Commit 0b950d3 (Input: tsc2005 - add open/close) introduced a
locking issue with the ESD watchdog: __tsc2005_disable() is calling
cancel_delayed_work_sync() with mutex held, and the work also needs the
same mutex.

Fix the problem by using mutex_trylock() in tsc2005_esd_work(). If the
mutex is taken, we know we are in the middle of disable or enable and
the watchdog check can be skipped.

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

diff --git a/drivers/input/touchscreen/tsc2005.c b/drivers/input/touchscreen/tsc2005.c
index 2a9a726..cbf0ff3 100644 (file)
--- a/drivers/input/touchscreen/tsc2005.c
+++ b/drivers/input/touchscreen/tsc2005.c
@@ -477,7 +477,14 @@ static void tsc2005_esd_work(struct work_struct *work)
        int error;
        u16 r;
 
-       mutex_lock(&ts->mutex);
+       if (!mutex_trylock(&ts->mutex)) {
+               /*
+                * If the mutex is taken, it means that disable or enable is in
+                * progress. In that case just reschedule the work. If the work
+                * is not needed, it will be canceled by disable.
+                */
+               goto reschedule;
+       }
 
        if (time_is_after_jiffies(ts->last_valid_interrupt +
                                  msecs_to_jiffies(ts->esd_timeout)))
@@ -510,11 +517,12 @@ static void tsc2005_esd_work(struct work_struct *work)
        tsc2005_start_scan(ts);
 
 out:
+       mutex_unlock(&ts->mutex);
+reschedule:
        /* re-arm the watchdog */
        schedule_delayed_work(&ts->esd_work,
                              round_jiffies_relative(
                                        msecs_to_jiffies(ts->esd_timeout)));
-       mutex_unlock(&ts->mutex);
 }
 
 static int tsc2005_open(struct input_dev *input)